// int pulse = 30; //visible, but a clear line
// int pulse = 40; //visible, a thick line (no smoke)
//int pulse = 50; //very visible, quick respons
int pulse = 100; //very visible, quick respons

void setup() {
  pinMode(4, OUTPUT);
  pinMode(5, OUTPUT);
}

void loop() {
  digitalWrite(4, 1); // set the LED on GPIO 4 ON
  delay (pulse);
  digitalWrite(4, 0); // set the LED on GPIO 4 OFF
  delay (100);
  
  digitalWrite(5, 1); // set the LED on GPIO 5 ON
  delay (pulse);
  digitalWrite(5, 0); // set the LED on GPIO 5 OFF
 delay (100);

}